Method of treating iron ore.



Patented Aug. 1o, 1909.

J T JONES v METHOD 0F TREATING IBOH OBE. APPLIUATIOI VlIlInIlI) 'IAL' 1 8, 1909.

UNITED STATES PATENT oEEroE.

JOHN T. JONES, OF IRON MOUNTAIN, MICHIGAN, ASSIGNOR TO JONES STEP-PROCESS COMPANY, OF DULUTIEL' MINNESOTA, A CORPORATION OF MINNESOTA.

METHOD or4 'mauri-NG moN ons.

' Specification of Letters atent.

Patented Aug. 10, 1909.

i, .Application tiled January 18, 1909. Serial No. 473,003.

To all whom 'it may concern:

Be it known that I, JOHN TJJoNEs," a citi zen of the UnitedStates, residing at Iron Mountain, in the county of'Dickmsonand State of Michigan, have invented a new and useful Improvementin Method of` Treating Iron Ore, of which the following is a specification. I

My invention relates to an improved method of treating oxid of iron ores for the purpose of metallizing the oxid constitu# ents and causing them to agglomerate and thus become-isolated from the slag-malng constituents, thereby converting the ore into sponge for subsequent treatment, under higher temperature, .wherein the metallic irondand slag-making. constituents are separate In carrying out my invention I prefer to employ a furnace, in the form 'of an inclined rotary tube lined throughout with tire-brick, or the like refractory material, and 'a gasproducer which generates and discharges.

hot reducinggas into the lower end of the tube. Inter-posed between thegas-producer and tube is-al stationary 'dischargefhopper in which the tube tits and'rotates at its lower end. The tube at its upper end rotates in a chamber communicating with a chimney. Extending through the sa-idchamber is a feed-chute into which ore and coal supplying hoppers discharge.

The natural temperature of the gas, from' the gas-producer entering the lower end of the furnace vor the tube, is approximately 1200 F. A controlled quantlty of air is A admitted intol the tube with the gas and while this lowers the reducing quality of the 'gas-mixture, it raises the temperature thereof to, say, from 2000o F. to 2200o F. The gaseous mixture passes entirely through the tube and discharges into the chimney. The ore to be treated is preferablycrushed, if necessary, to say, from one-quarter to onehalf inch mesh, and is fed with a limited quantity of coal, which may also be prehminarily crushed, into the upper end of the rotatin tube. 'When employing'bituminous coa I prefer to feed, say, five hun- `dred pounds thereof to each ton of ore,

feeding the ore and coal in a manner to cause them to mix more or less intimately as they descend into the tube. In the rotation of the inclined tube the ore and coal mixture is moved gradually downward toward the lower end of the furnace, the speed of movement being governed by the speed of rotation of the tube.

My present invention lies in introducing bituminous coal or the like carbonaceousmaterial, with the ore, in a loose state, into the upper or feed end of the furnace, to enhance the reducing atmosphere above that 'part of the tube where final, or approximately complete, reduction of the iron oxids occurs, and then subjectingthe reduced ore to a gradually increasing and non-oxidizing temperature, reaching a point approximately wherein the slag-making constituents become viscous or plastic and run together as they separate in the mass from the reduced iron constituent. As the ore and coal mixture passes through the upper part of the tube it is subjected to a more or less gradually increasing temperature commencing, say, at

about 600 F., and increasing until the volatiles in the coal are burned out, combustion being supported by the oxygen freed from the ore. This reduction becomes complete before theY ore reaches a temperature at which it will meltas an oxid and before the slag-making constituents become viscous or pasty to any material extent. Reduction of the iron oxids may be said to be complete in the furnace 'when the ore in a reducing atmosphere reaches a temperature of, say, between 14000 F. and 15000 -F If the ore were then brought into contact with-atmospheric air it would oxidize very rapidly. I

have found that by subjecting the ore after reduction toa non-oxidizing atmosphere of gradually lncreaslng temperature, reaching a inal heat of from 2000o F. to 2200o F.,vr the iron becomes fixed in its metallized state A and will not readily oxidize when brought into contact with atmospheric air. This temperature is insufficient to render the slagmaking constituents fluid, so that the mass is discharged from the lower end of the furnace in the form of sponge. The sponge may be allowed to cool or it may be treated immediately in an open hearth, balling or olther furnace, to free the metal from the s ag.

In the accompanying drawing I show, for purposes of illustration, apparatus suitable for carrying out my improved method; the View being partly in elevation, partly in section', and diagrammatic in its nature.

The figure shows the furnace or tube l in controllable air-inlet. The gas from the gasfrom the ore.

.the chamber 6 is a producer has a natural. temperature approximating 12000 F. Suflicient air is admitted through the twyer 5 to promote combustion of the producer-gas and raise it to a temperature of, say, 2200O F. The oxygen of the air admitted at the twyer will be taken upby the producer-gas and the hot atmosphere moving upward in the furnace will still be of a more or less reducing na ture. The upper end of the furnace or tube rotates in a stationary chamber G having an outlet 7 to a chimney 14. Passing through feed-chute 8 having a hopper-top 9 and closed by a bell-valve 10. Discharging into the hopper 8 are the chutes 11 and 12, one for ore and the other for coal.

Coal and ore are discharged simultaneously into the hopper 9 in proportions of, say, ve hundred pounds of coal to the ton of ore, though these proportions may be varied as desired. `When the bell-valve 10 is lifted, the ore and coal mixing together as they descend, fall into the upper end of vthe furnace where the mixture is subjected to a temperature of, say, from 600o F. to 700 F. In the rotation of the furnace the mass is moved slowly downward, the coal being ignited and taking up the oxygen Combustion of the coal is completed, in practice, when the mass has moved, say, one-third of the distance down the tube, and the absorption of the oxygen of the orefin supporting combustion of the fuel, and the furtherabsorption thereof by theV hot reducing-gas, passing across and through the mass from the lower end of the tube, completes reduction of the ore when it has reached approximately the middle of the tube. From there on, the ore is subjected to a gradually increasing temperature, in a non-oxidizing atmosphere, until it approximates, say, 2000 F., and isP discharged into the hopper 2. As preferably none of the constituents of the ore is rendered, more than viscous or pasty before being discharged, thc

spongy product will not adhere to the wall of the tube, at least not to an extent which renders its removal difficult to accomplish. Beneaththe hopper 2 is a track on which cars 15 may be run to receive the product when the valve 13 is opened. What I claim as new and desire to secure byLetters Patent is-V 1. The method of treating iron-ore, which consists in mixing carbonaceous material therewith, then advancing the mixture through a highly heated' non-oxidizing atmosphere, to consume the carbonaceous niaterial and support its combustion with oxygen from the ore, thus reducing the ore, then advancing the reduced mass through a still more highly heated non-oxidizing atmosphere to lix the metal constituent without meltingthe slag-making constituents.

2. The method of treating iron-ore, which consists in mixing carbonaceous material therewith, then advancing the mixture through a highly heated non-oxidizing utmosphere, to consume the carbonaceous material and support its combustion with oxygen from the ore, thus reducing the ore, then advancing the reduced mass through a non- .oxidizing atmosphere of gradually-increasing temperature approximating without reaching the melting point of the slag constituents.

JOHN T. JONES. In the presence of- C. T. WINEGAR, W. G. JONES. 

